Pump apparatus for slurry and other viscous liquids

ABSTRACT

A peristaltic pump is operated by squeezing rollers pressing on an elastic tube supported inside a semicylindrical chamber. The collapsed tube is reopened by traveling side rollers which press the tube transversely. This expedites refilling and increases pump capacity. A surge chamber consisting of an elastic hollow cylinder housed inside a tubular housing provided with inwardly projecting annular ribs smooths out both minor and major surges in flow of the viscous material.

United States Patent Clay et a1.

[54] PUMP APPARATUS FOR SLURRY AND OTHER VISCOUS LIQUIDS [72] inventors:Robert B. Clay, Bountiful; William A.

Doering, Salt Lake City, both of Utah [73] Assignee: lreco Chemicals[22] Filed: Mar. 4, 1970 [21] Appl. No.: 16,359

[52] US. CL ..4l7l477 [51] ..F04b43/l2 [58] Field of Search ..417/477,476, 475, 474, 900;

[56] References Cited UNITED STATES PATENTS Cromwell et a1 V g [45] Mar.14, 1972 2,987,004 6/1961 Murray .417/477 2,818,815 1/1958 Corneil..417/475 Primary Examiner-Carlton R. Croyle Assistant Examiner-RichardSher Attorney-Edwin M. Thomas [57] ABSTRACT A peristaltic pump isoperated by squeezing rollers pressing on an elastic tube supportedinside a semicylindrical chamber. The collapsed tube is reopened bytraveling side rollers which press the tube transversely. This expeditesrefilling and increases pump capacity. A surge chamber consisting of anelastic hollow cylinder housed inside a tubular housing provided withinwardly projecting annular ribs smooths out both minor and major surgesin flow of the viscous material.

6 Claims, 5 Drawing Figures Patented Mmh 14, 1972 3,649,138

INVENTORS ROBERT E. CZAY V/uz/AM 4 fiofmve ATTORNEY PUMP APPARATUS FORSLURRY AND OTHER VISCOUS LIQUIDS BACKGROUND AND PRIOR ART Variousdevices have been proposed in the past for pumping viscous fluids suchas explosive slurries. Such slurries are frequently very corrosive andabrasive to machinery and pumping operations involving them havepresented serious problems in many instances because of their reactivesolutions and also because of the nature of the suspended solids theycontain. The pumping of blasting slurries is only one good example ofthe types of problems frequently encountered but analogous problemsarise with other viscous liquids.

Slurry blasting agents commonly comprise a gelled liquid media in whichsolid particles of metal, such as aluminum, and/or carbonaceousmaterials such as ground gilsonite or coal, sugar, and the like, aresuspended These viscous materials are often quite heavily loaded withsolid particles. In addition to metals and other fuel particles,granules of undissolved salts, such as ammonium nitrate, sodium nitrate,and the like, are frequently included in blasting slurries, althoughmajor proportions of these oxidizer salts usually are in solution. Thesesalts are corrosive as well as abrasive.

Because of the abrasive character of the solid materials, the viscous,stringy and sometimes lumpy nature of the whole mixture, and thedifficulty of handling them with more conventional equipment, there areadvantages in using peristaltic pumps. These pumps are well known inprinciple, and are used for a variety of purposes. In pumping thick orviscous slurries, however, cavitation and other flow hindrance problemsarise because of their slow flow properties. A peristaltic pumpnecessarily depends on successive squeezing and opening up of thecollapsible tube or channel member to draw in a continuing supply of thematerial being pumped. With heavily loaded or viscous slurries, therubber tubes or hoses which are used as tubes or channel members, oftendo not spring open rapidly enough to draw in the sluggish flowingmaterial to be pumped so as to refill the tube. As a result, the pumpoperates inefficiently or discontinuously. At best, there tends to be apulsating or intermittent type offlow.

An important aspect of the present invention is the provision of a morepositive means by which the slurry may be drawn into the peristaltictube. Rollers engaging the side edges of the flattened, emptied tube areused to open it up into a rounded, or approaching rounded, position soas to cause the tube to refill with slurry after the squeegee rollershave passed over it.

Even with peristaltic pumps, there are pressure surges, especially withthe more viscous or heavily loaded slurries. These may be caused byvariations in viscosity, solids loading, flow irregularities, etc.Pressure pulsations interfere with manipulations of the delivery hose,as when blasting slurry is being pumped into boreholes. In some casesthey are severe enough to damage the pumping apparatus and even to burstthe delivery hose. The latter, of course, can involve serious dangers tooperating personnel and in any case it is essential that such pressuresurges be minimized and eliminated as far as possible. The pumpingapparatus often is associated with mixing equipment as is commonlymounted on a mobile vehicle, such as a truck or trailer where powerequipment is available for driving the pump.

Surge chambers are known in the prior art, including elastic drums,tubes or cylinders which can yield and thus expand or contract toaccommodate variations in flow velocity and pressure. Various types ofpneumatic pressured surge chambers are known, also. However, it is mostundesirable to have surges accumulate in substantial volumes. Forexample, when an operator is filling a borehole with explosive slurry,it is important for him to be able to start and stop the flow quickly,e.g. to avoid spillage or overflow. An expansive surge chamber, where asubstantial volume of slurry can accumulate, makes close control moredifficult. It is highly desirable to be able to smooth out low or highpressure surges without accumulating relatively large masses of theviscous liquid in a surge chamber. An important object of the presentinvention is to be able to accomplish this.

While the surge chamber of the present invention is particularlysuitable for the peristaltic pump, it is suitable also for use withreciprocating and other types of pumps where the pulse volume is notexcessive. The surge chamber of the present invention is designed toaccommodate small pressure surges with minimal volumetric expansion andto accommodate much larger surges in pressure with relatively littlefurther volume expansion. This is accomplished by using an elastictubular chamber member and surrounding it with spaced annu lar confiningrings. Expansion of the tube, merely enough to bring its walls intocontact with the rings, requires relatively small pressure increase.Further expansion, involving stretching of the tube walls between rings,or beyond rings, requires much larger pressure increments.

SUMMARY This invention comprises a collapsible tube which forms a flowchamber for slurry or other viscous or heavily loaded or thickenedliquids, positioned inside a cylindrical or part-cylindrical surface.Traveling squeeze or squeegee rollers, orbiting around a central axiswhich corresponds with the axis of the cylindrical surface, press thecontents of the tube forward through a control chamber and into a surgechamber. From the surge chamber, the material may be delivered to aborehole or any other receptacle to be filled.

The collapsible tube, in the form of a rubber or other elastic member,tends to reopen after the squeegee rollers have passed over it. However,the viscous contents may tend to cause the inner walls to adhere to eachother and the sluggish flow properties of the material being pumped tendto prevent rapid reopening of the tube. To overcome these tendencies,traveling rollers are provided to press on the edges of the flattenedtube and assist it in reopening. This expedites considerably the flow ofthe viscous liquid into the tube, preparatory to the next flatteningaction of the main pressure or squeeze rollers.

The control chamber includes means for determining pressure applied tothe material being pumped, means for releas ing the material through alateral vent when this is needed, and a blow-down connection, e.g., foradmitting air or other fluid to remove material from the surge chamberand the delivery line or hose.

The surge chamber comprises an expandable tube of rubber or similarelastic material, preferably rather thick-walled, strong enough tocontain high pressure but elastic enough to expand moderately at lowpressure and more at high pressure. Surrounding this tube with anannular space between is a strong-walled chamber, provided with spacedinwardly projecting annular ring elements which almost contact theexpandable tube, when in its normal relatively undilated condition. Onexpansion by a moderate pressure pulse, the tube dilates to contact therings which largely prevent further expansion until a much strongerpressure surge forces the tube to stretch into narrow zones between orbeyond the confining annular rings. Ribs ofother shapes may replacerings.

BRIEF DESCRIPTION OF DRAWINGS FIG. I is a side view, with certain partsin section and certain parts removed, of a preferred embodiment ofperistaltic pump, according to the present invention.

FIG. 2 is a transverse sectional view taken substantially along line 2-2of FIG. 1.

FIG. 3 is an enlarged detailed view in section, taken substantially online 3-3 of FIG. 1, showing the rollers which help to open up theperistaltic tube after its contents have been pressed out by thesqueezing rollers.

FIG. 4 is a cross-sectional detail view through the control chamber,being taken substantially along the line 44 of FIG. 1.

FIG. 5 is a fragmentary view showing a side view of the opening rollersfor the peristaltic tube.

DESCRIPTION OF PREFERRED EMBODIMENT The pump per se consists of a moreor less drum-shaped frame member 5 in which a rotating wheel member 6 ismounted on a hollow axle 7 to which it is keyed at 8. The wheel 6comprises a hub element 9 and integral flange elements 10 and 11. Theaxle 7 is driven by an appropriate prime mover shown herein as a motor12 secured to extension 13 of axle 7, mounted in antifriction bearings14 and 15. A hydraulic motor is preferred for operating this particularunit in pumping slurry explosives because it offers less hazards than anelectric motor. However, any appropriate prime mover can be used, e.g.,electrical, gasoline driven, etc., depending on the circumstances andhazards involved.

Wheel 6 carries a pair of squeeze rollers 19 rotatably mounted oneccentric shafts 20 between the plate flanges 10 and 11. That is to saythat the shafts 20 have reduced end portions 16 and 17 which areeccentric with respect to the main shafts 20. The ends 17 are mountedfor free rotation in the right flange 11 but the left end 16 (as seen inFIG. 2) of each shaft passes through a bushing 21 concentric and coaxialwith the ends 16 and 17, fitted into an enlarged opening 18 in leftflange 10 of main wheel 6. A somewhat larger disc 22 is keyed orotherwise nonrotatably attached to end portion 16 so that eithereccentric shaft 20 can be rotated to various positions by rotating disc22. The latter can be fixed in the desired position by inserting alocking bolt 23 into the appropriate one of several holes in disc 22,being screwed into a threaded opening in the flange 10. By this means.the pressure of the squeeze or squeegee rollers 19 on the peristaltictube 24 can be adjusted as desired. A nut 26 holds the shaft 20 tightlyattached to disc 22.

The peristaltic tube 24 extends from an inlet connection 28 at thebottom of frame 5 along a horizontal course and then follows theinterior of semicylindrical or drum surface 29 of member 5 to the topwhere it extends horizontally to the right to an outlet connection 30.Surface 29 is wide enough to support or back up the tube 24 when fullyflattened by the rollers 19. Outlet connection 30 is firmly connected totube 24 and is secured to frame member 5 by an arcuate locking flange 31which fits into an annular groove 32 in coupling 30.

The tube 24 is a strong elastic hose or cylinder of rubber or similardeformable and elastic material, which may be suitably reinforced byfabric or other fibrous material, if desired. Its elastic propertiestend to expand it to a normal round or nearround open condition after asqueezing roller has passed by.

The inlet end coupling element 28 preferably is of the quick-connecttype, so that a hose or pipe connection from a supply tank or a mixingstation can readily be attached or detached.

While tube 24 is or tends to be self-reopening, mechanical means areprovided to help and accelerate such reopening after each passage of asqueeze roller 19. Clamped between bearing brackets 42 and the innersurfaces of flanges 10 and 11 are the shafts 43 on which edge pressingrollers are mounted for free rotation. See FIG. 3, also FIG. 5. Theserollers are arranged opposite each other in pairs and two pairspreferably are used to follow each of the main squeeze rollers 19, asshown in FIG. 1. While two squeeze rollers 19 are shown in FIG. 1, andthis is the preferred arrangement, the pump will operate with only one,and three or more may be used, if desired. The side or tube openingrollers, of course, are used in such numbers and arrangements asrequired to open up the tube 24 after each squeezing operation.

The outer end of each roller 40 is beveled, or tapered, as indicated at44, so as to engage the tube at a gradual angle and avoid damage to thetube. The second roller of each pair can be set inward, if desired,towards the tube 24 with respect to the first roller so that it furthernarrows the width of the tube which can be accommodated between theopposed rollers.

The rollers are so positioned radially with respect to the main axle 7that they properly contact the edges of tube 24.

The structure so far described operates as follows: Slurry flows inthrough coupling 28 into the collapsible peristaltic tube 24. Assumingthat this tube is open or opening, its expansion creates a partialvacuum which assists in drawing in the slurry or other liquid to bepumped from a source of slurry supply, not shown. It will be understood,of course, that the source of slurry supply sometimes may be under somehydrostatic pressure, which helps to cause the material to flow into thetube. Assuming first that the tube is full or substantially full ofslurry, the rotation of wheel 6 around its central axis, as it is drivenby shaft 7, rolls the squeeze rollers 9 around and against the inside ofthe peristaltic tube, pressing it against surface 29, FIG. 2, andsqueezes the contents forward in clockwise direction, FIG. 1, throughthe outlet connection 30. The flattened tube thereafter is partiallyreopened by rollers 40.

From the pump, the slurry passes through outlet connection 30 through anelbow connection 51 and into a check-valve structure 52 which comprisesa ball check valve 54 operating against a seat 56. This valve preventsback-flow of the slurry in case the pump is stopped, or in case of anyother discontinuity in feeding slurry to the valve.

From check valve 52, another elbow connection 60 carries the slurry tocontrol chamber structure 62 which has another quick connector 63similar to connector 28.

As seen in cross section in FIG. 4, control chamber member 62 has aresilient diaphragm 64 across a top opening 65. Diaphragm 64 is clampedin place by a ring 66 held by bolts 67. A threaded opening 68 isprovided for connecting a signal line 69 (see FIG. 1) which transmits apressure reading from the diaphragm to an appropriate pressure gauge(not shown). By this means, the pressure on the slurry can be notedand/or recorded.

Member 62 also has a threaded drain or back-flow opening 70 throughwhich the slurry or other liquid may be discharged or withdrawn througha suitable line 71 controlled by valve 72. This valve, normally, isclosed. Through a side opening 73, also threaded, connection may be madeto a pneumatic hose or other source of fluid pressure. By applying eachpressure, the residual slurry or liquid in the outlet line and deliveryhose, beyond check valve 54, may be blown out or discharged.

The upper part of FIGS. 1 and 2 show a surge chamber which consists ofan elastic tubular inner member 81 formed of gum rubber or othersuitable strong elastic material, having not only a high tensilestrength, but being stretchable to at least twice or three times itsnormal diameter without rupture. In a typical case, this tube 81 may bean elastic rubber tube having a wall thickness of one-eighth toone-fourth-inch or more and being 1 /2 to 3 inches or more in internaldiameter. it may be made in various sizes for different purposes. Alength of this tubular material 81 is connected by clamps 83 to theconnecting outlet of chamber 62 mentioned above and to an outlet line 87through a quick release connector 85. In normal operation of the pumpalready described, pumping of the viscous fluid material forces valve 54open and the material flows through the other connection alreadydescribed. Thus, the slurry or viscous liquid is pumped through theexpansible conduit 81 and into its outlet line 87. Where this materialis an explosive slurry, the line 87 may constitute or be connected to along delivery hose whereby the slurry may be pumped into boreholes forblasting in large mining operations. As already noted, the pump can beused for other and analogous materials and is not limited to use withexplosive or other slurries.

Surrounding the tubular conduit 81 but annularly spaced therefrom at asuitable distance d, is a rigid-walled tube 89. The latter may be ametal pipe, such as aluminum or steel of sufficient wall strength towithstand any pressure that can reasonably be expected from the pump.This surge chamber can be used also with other pumps or pressure sourcesconnected to its inlet as already mentioned.

Arm

A plurality of ring members 91, preferably three as shown, are formedinside the rigid-walled conduit 89. They may be separate and heldtherein by friction or they may be integral with the wall member 89.These are preferably cast or formed with the rigid tube 89. However,they may be separate metal rings or other plastic material than rubbermay be used. They are spaced in such a manner that some expansion of thetube 81 between them may be accommodated. When the tube 81 is not undersubstantial pressure, it preferably does not quite touch the rings 91,although it may be in light contact therewith, if desired. The spacingbetween the rings like their number depends on the magnitude of thepressure to which the tube 81 is to be subjected, on its material andwall thickness, and also on the material of which rings 91 are formed.In normal operation, it may be expected that the tube 81 would beexpanded by a moderate pressure surge into contact with the innerannular surfaces of the rings 91. Expansion by much higher pressure isindicated by the dotted line 92, FIG. 1. The surge chamber is mounted onbrackets 94, 95, bolted to the top of frame 5 through angle foot members96, 97.

When a strong pressure surge is applied to the tube 81, it expands tocontact the ring members 91. Between adjacent pairs of ring members itis expanded even further, bulging between the rings to an extentdetermined by the pressure and the elasticity and tensile strength orresilience of the tube material 81. For example, a surge pressure two tofour times as great or even greater than that required to expand thetube to mere contact with rings 91 is required to expand the tubesignificantly into corrugations between the ring members 91, as shown at92 in FIG. 1.

in a typical structure tested in accordance with this invention, a2-inch gum rubber hose, having a wall one-fourth-inch thick, was firstconnected inside a 4-inch internal diameter metal pipe, which wasotherwise unobstructed. The connections were substantially as shown inFIG. 1, with the pipe 89 spaced about 1 inch from the outer wall of thetube 81 when there was no pressure. Under normal operation and atmoderate pressure, pumping slurry with a peristaltic type pump, thematerial flowed smoothly and the arrangement without rings 91 wassatisfactory.

Another model was built using inside a 5-inch pipe a 2%- inch insidediameter gum rubber tubing with walls one-half inch thick in theirnormal, unexpanded condition. At 30 p.s.i. pressure at the end of adelivery hose, this tubing expanded to fill the casing which surroundedit. As pressure of 30 p.s.i. was exceeded, however, there was no furtherroom for expansion and strong surging occurred in the delivery hose.This surging caused the hose to whip badly and might have burst a hoseof moderate strength.

The system was first tested by pumping water, which is less compressiblethan slurry because slurry normally contains some aeration. The hosepressure on the liquid after passing through the surge chamber variedonly about 2 p.s.i. in surges from an initial starting pressure of 0 upto about 30 p.s.i.g. pumping pressure. However as pumping pressure wenthigher, surges would suddenly jump to as high as 90 psi, then droppingback to 30 p.s.i. This was repeated every half revolution of theperistaltic pump. The simple surge chamber thus described was thereforequite suitable as a surge absorber at working pressures up to 30 p.s.i.It was completely inadequate at pressures above 30 p.s.i.

On confining the tube just described with the series of spaced rings inthe manner shown in FIG. 1, the rubber tubing was normally stretched outinto contact with the rings but not greatly beyond them at a pumpingpressure of 30 p.s.i. When stronger surges came along, the tube 11 wasbulged or corrugated between the rings, as shown in dotted lines 92 butincrements of pressure on the delivery hose were still very low, of theorder of 2 or 3 pounds, as compared with as much as 60 pounds in thecase described above.

When pumping water at 30 p.s.i. with the peristaltic pump and surgechamber of this invention, pressure would sometimes drop to 20 p.s.i.,but not go appreciably above 30 p.s.i. When pumping at a nominalpressure of p.s.i., the pressure normally did not drop below 60 p.s.i.during the low pressure cycle of the surge.

(2) Good improvement -needle did not strike peg.

(3) Nearly constant -fine for low pressure pumping.

(4) Some fluctuations but not objectionable, considering pumpingpressure.

(5 Gauge needle struck stop peg.

(6) Very large pressure fluctuation destructive over a period of time.

(7) Big improvement over (6).

With reciprocating type pumps, pressure surges are expected to besomewhat greater. It is often desirable to use a somewhat largerexpansion chamber of the type shown in FIG. 1. With the structuresshown, the pressure surge may be confined to desired low levels byadapting the size of the chamber to the volumetric magnitude of typicalsurges. It has been pointed out above that large volumetric expansion isundesirable. With a reciprocating pump, these surges, of course, arelarger than in the case of peristaltic or other continuous flow devices.A reasonably steady flow at the end of the hose is desired, and it isdesirable, also, to be able to cut off flow rather quickly withoutrupturing the tube 81 or the delivery hose, or doing damage to the pump.

As pointed out above, use of the confining rings around the rubber tubemakes it possible to accommodate surges at operating pressures of two tofour times or more those which are required merely to expand the tubeinto contact with the rings. The number of rings obviously may be variedwith different diameters and lengths of tubing 81. While annular ribs orrings are preferred, such as shown at 91, it will be understood thatribs which will extend spirally, or axially may be used. Grids ofriblike projections may be used in some cases. The annular ribs usuallycontrol the tube 81 better and place less strain on it.

The invention described above offers outstanding advantages in smooth,uniform flow. This is desirable and frequently is very important indelivering blasting slurry into boreholes. It is desirable, of course,to be able to control the flow with reasonable precision, and it isimportant to avoid whipping and other malfunctions associated with highpressure surges.

It will be obvious that modifications mentioned above and others notmentioned may be made by those skilled in the art without departing fromthe spirit and purpose of the invention. It is intended to cover theinvention and obvious variations and modifications as broadly as theprior art permits.

What is claimed is:

l. A peristaltic pump apparatus for fluids such as slurries and the likewhich comprises, in combination, an arcuate channel in a frame memberadapted to receive and house a peristaltic tube, a collapsibleperistaltic tube fitted into said channel and having an inlet endconnectable to a source of material to be pumped, a rotary carriermounted concentrically with said channel, roller mounting meansincluding an eccentric adjustable support secured to said carrier, asqueeze roller rotatably journaled on said mounting means for pressingand collapsing said peristaltic tube and thus forcing its contentsforward from said inlet end towards an outlet, and plural successivepairs of tube opening rollers also carried by said rotary member andmounted progressively closer together to assist in opening the collapsedtube after the squeeze roller has passed along by pushing the edges ofsaid collapsed tube towards each other in progressive steps thereby toaccelerate refilling of said tube by said by said material from saidinlet end.

2. Apparatus according to claim 1 which includes a plurality of squeezerollers mounted on said rotary carrier and a plurality of pairs of saidopening rollers following each squeeze roller.

3. Apparatus according to claim 1 which comprises an elastic surgechamber connected to the outlet of the peristaltic tube to smooth outthe pump output.

4. Combination according to claim 1 which comprises a check valveconnected to the pumpoutlet and a surge chamber connected to said checkvalve.

5. A pump according to claim 1 which includes a surge chamber of lowvolume expansion characteristics comprising an axially extending elasticinner chamber wall member, an outer chamber wall member coaxial with andspaced annularly from said inner chamber, and a plurality of spaced ribelements located in the annular space between said chambers and adaptedto limit expansion of the elastic inner chamber wall member.

6. A pump according to claim 5 wherein the spaced rib elements are inthe form of spaced annular ring elements protruding inwardly from theouter chamber wall member.

1. A peristaltic pump apparatus for fluids such as slurries and the likewhich comprises, in combination, an arcuate channel in a frame memberadapted to receive and house a peristaltic tube, a collapsibleperistaltic tube fitted into said channel and having an inlet endconnectable to a source of material to be pumped, a rotary carriermounted concentrically with said channel, roller mounting meansincluding an eccentric adjustable support secured to said carrier, asqueeze roller rotatably journaled on said mounting means for pressingand collapsing said peristaltic tube and thus forcing its contentsforward from said inlet end towards an outlet, and plural successivepairs of tube opening rollers also carried by said rotary member andmounted progressively closer together to assist in opening the collapsedtube after the squeeze roller has passed along by pushing the edges ofsaid collapsed tube towards each other in progressive steps thereby toaccelerate refilling of said tube by said by said material from saidinlet end.
 2. Apparatus according to claim 1 which includes a pluralityof squeeze rollers mounted on said rotary carrier and a plurality ofpairs of said opening rollers following each squeeze roller. 3.Apparatus according to claim 1 which comprises an elastic surge chamberconnected to the outlet of the peristaltic tube to smooth out the pumpoutput.
 4. Combination according to claim 1 which comprises a checkvalve connected to the pump outlet and a surge chamber connected to saidcheck valve.
 5. A pump according to claim 1 which includes a surgechamber of low volume expansion characteristics comprising an axiallyextending elastic inner chamber wall member, an outer chamber wallmember coaxial with and spaced annularly from said inner chamber, and aplurality of spaced rib elements located in the annular space betweensaid chambers and adapted to limit expansion of the elastic innerchamber wall member.
 6. A pump according to claim 5 wherein the spacedrib elements are in the form of spaced annular ring elements protrudinginwardly from the outer chamber wall member.